This invention relates to an air cleaner suitable for use with an internal combustion engine. It is impossible for an air cleaner of an internal combustion engine to achieve high performance unless its filter element is mounted in a correct position and suitably supported for operation.
For instance, in one type of air cleaner of an internal combustion engine known in the art, a filter element of rectangular shape is used and held in position within a casing by being shaped into a forwardly projecting convex form while being secured at its peripheral edge portion to the casing, to ensure that it achieves high filtering performance while maintaining air permeability at a satisfactory level.
In this type of air cleaner, two holding plate assemblies each consisting of a grid-like portion are used and one holding plate assembly is located in the front of the air cleaner forwardly of the filter element (on the air inlet side) and the other holding plate assembly is located in the rear of the air cleaner rearwardly of the filter element (on the carburettor side), and the grid-like portion of at least one holding plate assembly is bent in convex form so as to extrude forwardly at its middle portion to form and keep the filter element in a forwardly extruding convex form. If the holding plate assembly consisting of a convex-shaped grid-like portion is assembled with the casing of the air cleaner in such a manner that the assembly faces the wrong direction, the filter element would be compressed and brought out of action. Thus, it is necessary that caution be exercised to make the convex-shaped holding plate assembly face the correct direction when it is assembled with the casing.